Natural gas fuels alternative technologies
On Jan. 25, President Barack Obama delivered his State of the Union speech to the people of the United States of America. The speech included a strategy for implementing transportation based on alternative fuels during 2012 and beyond. One of the new goals will be the development of natural gas as an alternative fuel for transportation.
Obama flew to Las Vegas the day after his State of the Union address, and during his visit he showcased some of the companies providing vehicles and refueling infrastructure that will enable natural gas to become a widely used transportation fuel.
A company named Clean Energy has built seven natural gas refueling stations in Las Vegas that can convey methane to vehicle fuel tanks by compressing natural gas into a smaller space or by cooling and liquefying it. The Las Vegas sites are part of a network of liquefied natural gas refueling stations stretching from Los Angeles to Salt Lake City along Interstate 15. The company hopes to continue expanding its fuel station network from coast to coast.
Industrial-grade natural gas that comes through a household pipeline is composed of more than 80 percent methane, although it also can include small portions of ethane, nitrogen, oxygen and even water.
Natural gas condenses this mixture into an even larger concentration of 95 percent methane when it changes state to a liquid form at minus 261 degrees Fahrenheit. However, to maintain a liquid state at that temperature, natural gas must be stored in a double-walled, cryogenic tank that is pressure regulated. The liquid form is beneficial because it compresses the volume of natural gas by a factor of 600. A cryogenic storage tank can be transported on a truck and used in locations where there are no natural gas pipelines.
The gaseous form of methane also can be compressed to 3,600 pounds per square inch at standard ambient air temperatures to provide a usable fuel range that is comparable to a tank of gasoline. However, a special metal-jacketed, carbon-fiber tank must be built and engineered with extra containment strength to handle a highly pressurized volume of natural gas in this state.
These containers usually take the form of cylindrical pressure vessels that may cost 10 times more than a standard liquid gasoline tank. Although prohibitive for smaller consumer vehicles, the cost of a compressed or liquefied natural gas fuel tank is not as large a percentage of the overall manufacturing cost for a larger public transit bus or a tractor trailer.
MGM Resorts International has worked with Clean Energy to implement a fleet of 26 limousines fueled by compressed natural gas for the use of guests visiting CityCenter Las Vegas. The idea to use a cleaner- burning transportation fuel for a limousine fleet was conceived by Bobby Baldwin, president of MGM's CityCenter project.
Paul Berry, vice president of hotel operations at MGM Resorts International, worked with Duane Sinatra, executive director of Front End Services, to make the compressed natural gas-powered limousine fleet a reality. Since none of the worldwide automobile manufacturers at the time produced stock CNG-powered limousines, the management team contracted Krystal Enterprises to convert gasoline-powered Ford Lincoln Town Car platforms into CNG-powered limousines that were stretched as much as 10 feet.
To modify the stock 4.6-liter V-8 engines, stronger injectors and other kit components were needed to handle the greater pressure from the compressed natural gas fuel tanks that supply methane gas into each of the engine's combustion chambers. Three separate cylindrical fuel tanks, housed in the middle of the limousine, deliver 20 gallons of pressurized methane gas to the engine and provide comparable driving range of about 180 miles. Average daily usage for each limousine is about 82 miles per day. Refueling time is about five to eight minutes for the three tanks.
The limousine engine system also includes two alternators that provide extra electric power to the limousine cabin as well as two air-conditioning systems for the front and back of the vehicle to keep guests comfortable during hot Las Vegas summers.
The gasoline gallon equivalent price at a Clean Energy fueling station is about $1.89 per gallon compared with gasoline prices now heading above the $4 per gallon mark.
Berry compared the cost of fuel for the 26 CNG-powered limousines against the cost of fuel for 26 gasoline-powered limousines in CityCenter's fleet over a one-year period. He recorded a savings of $90,000 in fuel expenditures during 2011. This cost benefit from CNG should continue to improve as gasoline prices rise while natural gas prices continue to decline.
MGM Resorts International intends to install this technology at its other resort properties, including six limousines at Bellagio and six more at The Mirage within the next few months.
Stan Hanel has worked in the electronics industry for more than 30 years and is a long-time member of the Electric Auto Association and the Las Vegas Electric Vehicle Association. Hanel writes and edits for EAA's "Current Events" and LVEVA's "Watts Happening" newsletters. Contact him at stanhanel@aol.com
